Performance degradation due to probable (?) C2 issue

[Andrew Haley]

Hi,

On 28/07/2020 11:35, Сергей Цыпанов wrote:

> So my question is whether there's something wrong with compier of
> the original idea of improvement was wrong?

No, and (probably) no.

C2 uses a bunch of of heuristics. Here, it's detected that
CharArrayWriter::toString is large and has already been compiled so
there's no sense inlining another copy of it. This isn't necessarily
true, but it's a good guess. Try playing with InlineSmallCode: start
with =1000, and increases it from there to see if it helps.

-- 
Andrew Haley  (he/him)
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
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